refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
fs/btrfs/extent_io.c | 14 +++++++-------
fs/btrfs/extent_io.h | 3 ++-
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 3cf0b02..0702be6 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -68,7 +68,7 @@ void btrfs_leak_debug_check(void)
pr_err("BTRFS: state leak: start %llu end %llu state %u in tree
%d refs %d\n",
state->start, state->end, state->state,
extent_state_in_tree(state),
- atomic_read(&state->refs));
+ refcount_read(&state->refs));
list_del(&state->leak_list);
kmem_cache_free(extent_state_cache, state);
}
@@ -238,7 +238,7 @@ static struct extent_state *alloc_extent_state(gfp_t mask)
state->failrec = NULL;
RB_CLEAR_NODE(&state->rb_node);
btrfs_leak_debug_add(&state->leak_list, &states);
- atomic_set(&state->refs, 1);
+ refcount_set(&state->refs, 1);
init_waitqueue_head(&state->wq);
trace_alloc_extent_state(state, mask, _RET_IP_);
return state;
@@ -248,7 +248,7 @@ void free_extent_state(struct extent_state *state)
{
if (!state)
return;
- if (atomic_dec_and_test(&state->refs)) {
+ if (refcount_dec_and_test(&state->refs)) {
WARN_ON(extent_state_in_tree(state));
btrfs_leak_debug_del(&state->leak_list);
trace_free_extent_state(state, _RET_IP_);
@@ -641,7 +641,7 @@ static int __clear_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
if (cached && extent_state_in_tree(cached) &&
cached->start <= start && cached->end > start) {
if (clear)
- atomic_dec(&cached->refs);
+ refcount_dec(&cached->refs);
state = cached;
goto hit_next;
}
@@ -793,7 +793,7 @@ static void wait_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
if (state->state & bits) {
start = state->start;
- atomic_inc(&state->refs);
+ refcount_inc(&state->refs);
wait_on_state(tree, state);
free_extent_state(state);
goto again;
@@ -834,7 +834,7 @@ static void cache_state_if_flags(struct extent_state *state,
if (cached_ptr && !(*cached_ptr)) {
if (!flags || (state->state & flags)) {
*cached_ptr = state;
- atomic_inc(&state->refs);
+ refcount_inc(&state->refs);
}
}
}
@@ -1538,7 +1538,7 @@ static noinline u64 find_delalloc_range(struct
extent_io_tree *tree,
if (!found) {
*start = state->start;
*cached_state = state;
- atomic_inc(&state->refs);
+ refcount_inc(&state->refs);
}
found++;
*end = state->end;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index c16260c..9ea9338 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -2,6 +2,7 @@
#define __EXTENTIO__
#include <linux/rbtree.h>
+#include <linux/refcount.h>
#include "ulist.h"
/* bits for the extent state */
@@ -134,7 +135,7 @@ struct extent_state {
/* ADD NEW ELEMENTS AFTER THIS */
wait_queue_head_t wq;
- atomic_t refs;
+ refcount_t refs;
unsigned state;
struct io_failure_record *failrec;
--
2.7.4
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